Rubén Béjar

Metadata standard interoperability: application in the geographic information domain

Abstract The use of metadata expands on the opportunities for interoperability. Interoperability involves making multiple information sources access, manipulate and share data across their boundaries. Metadata descriptions from different domains are not semantically distinct but overlap and relate to each other in complex ways. As the number, size and complexity of the metadata standards grow, the task of facilitating metadata in different standards becomes more difficult and tedious. A possible solution for this problem is the creation of mechanisms that enable the translation of this information in order to make it conform to the different standards. These mechanisms are denominated “crosswalks” and the objective of this work is to present the process of “crosswalk-creation”, which has been used by a research team at the University of Zaragoza in order to translate information among some of the most extended standards for geographic information metadata.

A Web Ontology Service to facilitate interoperability within a Spatial Data Infrastructure: Applicability to discovery

Ontologies are used within the context of Spatial Data Infrastructures to denote a formally represented knowledge that is used to improve data sharing and information retrieval. Given the increasing relevance of semantic interoperability in this context, this work presents the specification and development of a Web Ontology Service (WOS), based on the OGC Web Service Architecture specification, whose purpose is to facilitate the management and use of lexical ontologies. Additionally, this work shows how to integrate this service with Spatial Data Infrastructure discovery components in order to obtain a better classification of resources and an improvement in information retrieval performance.

An architectural style for spatial data infrastructures

This work proposes an architectural style, a pattern, for spatial data infrastructures (SDIs). This style provides a tool and a shared vocabulary to help system architects to design these infrastructures, and facilitates the exchange of knowledge about them. This style is defined under the component‐and‐connector architectural viewtype, extending the client–server and shared‐data styles. The style has been created after analyzing six of the most relevant SDIs and geo‐service architectural proposals. Several architectural elements that these proposals have not properly addressed are considered. Three real projects, with published architectural views or models, have been examined to verify the applicability of the style. The proposed style offers a systematization and refinement of knowledge about SDIs, grounded in well‐known concepts in software architecture.

Availability of the OGC geoprocessing standard: March 2011 reality check

This paper presents an investigation about the servers available in March 2011 conforming to the Web Processing Service interface specification published by the geospatial standards organization Open Geospatial Consortium (OGC) in 2007. This interface specification gives support to standard Web-based geoprocessing. The data used in this research were collected using a focused crawler configured for finding OGC Web services. The research goals are (i) to provide a reality check of the availability of Web Processing Service servers, (ii) to provide quantitative data about the use of different features defined in the standard that are relevant for a scalable Geoprocessing Web (e.g. long-running processes, Web-accessible data outputs), and (iii) to test if the advances in the use of search engines and focused crawlers for finding Web services can be applied for finding geoscience processing systems. Research results show the feasibility of the discovery approach and provide data about the implementation of the Web Processing Service specification. These results also show extensive use of features related to scalability, except for those related to technical and semantic interoperability.

A Method to Derivate SOAP Interfaces and WSDL Metadata from the OGC Web Processing Service Mandatory Interfaces

Web Processing Services (WPS) expose processing functionality using Web Service technology. The WPS specification describes the interfaces to publish geospatial processes on the Web. It includes a platform-neutral and several platform-specific versions of its interfaces. Some of the platform-specific interfaces are mandatory and others are optional. In this paper, we present a method to support the automatic derivation of the optional SOAP interfaces and WSDL metadata from the mandatory ones in any WPS. These interfaces can then be used to facilitate the chaining of the WPS with other Web Services, using for example BPEL, and to improve the interoperability of these services. In addition to that, we have created a tool to validate the proposed method.

Discovering geographic web services in search engines

Purpose – There is an open discussion in the geographic information community about the use of digital libraries or search engines for the discovery of resources. Some researchers suggest that search engines are a feasible alternative for searching geographic web services based on anecdotal evidence. The purpose of this study is to measure the performance of Bing (formerly Microsoft Live Search), Google and Yahoo! in searching standardised XML documents that describe, identify and locate geographic web services.Design/methodology/approach – The study performed an automated evaluation of three search engines using their application programming interfaces. The queries asked for XML documents describing geographic web services, and documents containing links to those documents. Relevant XML documents linked from the documents found in the search results were also included in the evaluation.Findings – The study reveals that the discovery of geographic web services in search engines does not require the use of...

Spatial Data Infrastructures for environmental e-government services: The case of water abstractions authorisations

Environment-related authorisations are a relevant issue for environmental management. They require a considerable effort by the authorities, and this might result in substantial delays for the citizens. Implementing those authorisation processes by means of e-government services would improve efficiency and, consequently, citizen satisfaction. Environment-related authorisations usually require a variety of geospatial information, and have to deal with administrative areas which do not match physical and ecological ones. They also have to integrate heterogeneous information in different formats, data models and languages, and provided by distinct organisations, even from different countries. This paper discusses how Spatial Data Infrastructures (SDIs) can deal with these problems in the environmental domain, while improving the level of service provision in terms of e-government applications. This is even more relevant within the European Union where there is a legal mandate to establish an SDI to support environmental policies and activities with an impact on the environment. As a proof-of-concept, an application to request and manage water abstraction authorisations, based on an SDI, is demonstrated. This application is part of SDIGER, a cross-border inter-administration SDI to support the water framework directive information access for the Adour-Garonne and Ebro River basins, that was a pilot project for the EU INSPIRE Directive. The introduction of this transactional e-government service modifies the administrative process of granting authorisations: it allows to re-use the effort in data capture made by the applicants in their requests, facilitates the submission of more feasible applications and reduces the workload of the office staff.

Semantic interoperability based on Dublin Core hierarchical one-to-one mappings

The tendency of current cataloguing systems is to interchange metadata in XML according to the specific standard required by each user on demand. Furthermore, metadata schemas from different domains are not usually semantically distinct but overlap and relate to each other in complex ways. As a consequence, the semantic interoperability has to deal with the equivalences between those descriptions. There exist two main approaches in order to tackle this problem: solutions based on the use of ontologies and solutions based on the creation of specific crosswalks for one-to-one mapping. This paper proposes a hierarchical one-to-one mapping solution for improving semantic interoperability.

Applying Semantic Linkage in the Geospatial Web

The Semantic Web is an attempt to add meaningful annotations to Web resources, services and content that requires developing reference ontologies, which help to understand these annotations. The venue of the Web of Data makes the geographic information, which has become an important part of the current Web, widely usable.

A model driven approach for the development of metadata editors, applicability to the annotation of geographic information resources

Metadata are a key element for the development of information infrastructures because they facilitate the semantic description of contents and services. However, the diversity and heterogeneity of metadata standards have become a barrier for the generation of these metadata. Many metadata editors are not useful anymore because they do not support the latest version of metadata standards or the new profiles arisen in the market. Thus, this work proposes a model driven approach for the development of metadata editors, more focused on the generic treatment of metadata models than on the development of specific edition forms for a reduced set of metadata standards. This approach has been tested in the context of Spatial Data Infrastructures for the development of an Open Source tool called CatMDEdit. Additionally, the approach could be also applied to improve the efficiency of any metadata editor using a metamodeling development strategy.